Oil compositions containing amine salts of boro-diol complexes



eteni Feb. l4, l9

on. ooosrrrons comma a SALTS 0F BORO-DIOL COMPLEXE Charles E. Trautman,Cheswick, Pa, assignor to Gulf Research & Development Company,Pittsburgh, Pa, a corporation of Delaware No Drawing. ApplicationDecember 3, 1947, Serial No. 789,569

12 Claims. 3

This invention relates to oil compositions, and n particular concernsnew hydrocarbon oil com- Jositions having improved stabilitycharacterisics. including improved resistance to sludge- :ormation andimproved anti-corrosion properdes.

It is well known that hydrocarbon oils, par- ;icularly those of mineralorigin, have a tendency ao deteriorate and form sludge-like depositswhen tllOWEd to stand over long periods of time at moderately elevatedtemperatures, or in a relaively short time under service conditions suchis those encountered in modern intern-a1 comillStlOD. engines. This typeof deterioration is atributed to the oxidation of certain of the hydro-:arbons present in such oils. It is also known hat such oils tend topromote corrosion of metal \urfaces, particularly alloy bearingsurfaces, with which they come in contact during service. This ype ofcorrosion is in many cases believed to be we to the presence ofoxidation products formed ry deterioration of theoil rather than tocomonents of the oil itself.

It is an object of the present invention to pro- -ide oil compositionshaving improved resistance 0 deterioration and sludge-formation.

Another object is to provide oil compositions laving improvedanti-corrosive properties, paricularly with respect to alloy bearings.

A further object is to provide oil compositions I raving improvedservice characteristics.

A still further object is to provide means for mproving the generalstability characteristics of lydrocarbon oils without detracting fromtheir cad-carrying and lubrication qualities.

Other objects will be apparent from the fol- )wing detailed descriptionof the invention, and arious advantages not specifically referred toierein will occur to those skilled in the art upon mployment of theinvention in practice.

In accordance with the above and related obects, I have found that theamine salts of boroiol complexes are excellent stabilizing agents orhydrocarbon oils, and that compositions comrising hydrocarbon oilsnormally subject to dearioration through oxidation or other means andrelatively small amounts of such amine salts have greatly improvedresistance to sludge-formation and other manifestations ofdeterioration, including a tendency to promote corrosion of bearingalloys and the like. This improvement is secured with no loss ofload-carryingqualities, and in fact in certain instances the generallubrication characteristics are improved. The variousamine salts differamong themselves as to their" degree of effectiveness in imparting oneor more desirable properties to the compositions. For example, certainof such salts may be particularly efl'ective in reducingsludge-formation, whereas others may be more efiective in inhibitinghearing-corrosion. Others may secure one or both of these benefits andin addition improve lubrication properties. In general, however, all ofsuch salts act as stabilizing agents to improve the resistance ofhydrocarbon oils to deterioration during storage or service.Accordingly, the oil compositions provided by the invention areparticularly suited to use as lubricants in internal comdrasticdeterioration conditions. They are also useful as heat-transfer mediaand the like, e. g.,

transformer oils, where it is desired to maintain a high degree ofresistance to sludging over long periods of time. I

The amine salts which are employed as stabilizing agents in the oilcomposition provided by the invention are obtained by the directaddition of an organic amine to a boro-diol complex. The lattercomplexes are formed by reaction between boric acid and an organiccompound containing at least two hydroxyl groups, e. g., ethyleneglycol. The nature of the reaction and the configuration of thesecomplexes are not known with certainty, although in some instancesstructural formulae have been proposed. In general they are believed tobe chelate-type compounds containing the wherein R represents theresidue oi the dihydroxy compound. The present invention, however, is inno way limited by any theory concerning the structure of the boro-diolcomplexes whose amine salts are employed as stabilizing agents in thenew compositions.

The formation of the boro-diol complexes may be carried out simplylay-heating boric acid with an organic compound containing at least twohydroxyl groups until the theoretical amount of water is evolved fromthe mixture. The polyhydroxy compounds which may be reacted with boricacid in such manner include both aliphatic and aromatic compounds, 1.e., polyhydric alcohols such as ethylene glycol, diethylene glycol,propylene glycol, butylene glycol, trimethylene glycol, erythritol,glycerol, triethylene glycol, tetramethylene glycol, etc., andpclyhydric phenols such as catechol, resorcinol, orcinol,

beta naphthohydroquinone, dihydroxytoluene, phenylcatechol,ethylcatechol, etc. They may also be compounds in which one of thehydroxyl groups is part of a carboxyl group, e. g., salicylic acid,glycollic acid, melilotic acid, coumaric acid, and similarhydroxycarboxylic acids, or cyclic compounds such asdihydroxycyclohexane, dihydroxyfuran, etc. I

As previously mentioned, the amine salts which are employed asstabilizing agents in the oil compositions provided by the invention areformed by the direct addition of organic amines to the above-describedboro-diol complexes. This reaction may be carried out simply by heatinga mixture of the complex and the amine to a suitable reactiontemperature until reaction is complete. Usually the optimum reactiontemperature will be between about 50 C. and about 200 0., although thisrange is not critical and temperatures outside this range may be employed. If desired, the reaction may be carried out in the presence or"an inert solvent such as water, benzene, toluene, naphtha, etc. Also, ifdesired, the amine salts may be prepared directly from boric acid andthe desired organic amine and polyhydroxy compound without isoiation ofthe intermediate boro-diol complex by heating a mixture of the threereactants, either under anhydrous conditions as proposed in U. S. Patent1,975,890 or in the presence of water as disclosed by Boesken et al.,Rec. Trav. Chim., 37, 18a (1918).

Any organic amine may be employed in preparing the boro-diol complexsalts as just described. As examples of such amines, there may bementioned aliphatic and cycloaliphatic amines, including alkylolamines,such as methylamine, ethylamine, diethylamine, amylamine, tributylamine,ethanolamine, diethanolamine, triethanolamine, isopropanolamine,trimethylamine, laurylamine, hexadecylamine, ethylenediamine,diethylenetriamine, triethylenetetramine, cyclohexylamine,dicyclohexylamine, tristearylamine, guanidine, etc.; aromatic amines,such as aniline, naphthylamine, methylaniline, diethylaniline,toluidine, phenetidine, diphenylamine, triphenylamine,diaminodiphenylmethane, aminocresol, aminophenol, phenylenediamine,benzidine, amino-diphenyl, aminodiphenyloxide, diphenylguanidine,benzylamine, diphenylethylamine, etc.; and heterocyclic amines, such aspyridine, piperidine, aminobenzothiazole, morpholine,. etc.

The amine salts of the present class are ef- Iective as stabilizingagents for hydrocarbon oils in relatively small. amounts, e. g. from aslittle as 0.001 per cent by weight up to the limit of their solubilityin the oil, which is usually somewhat less than about 0.5 per cent'byweight.

Since it is usually desirable to provide compositions of maximumstability, 1. e., compositions 5 containing a maximum effective amount01' the stabilizing agent, the new compositions are usuallyprepared byadding the stabilizing agent to the oil in an amount in excess of thatsoluble .in the quantity of oil taken. After promoting as completesolution as possible through the use 01' agitation and/or heat, thecomposition is filtered to recover the undissolved stabilizing agent andto insure a homogeneous product. If desired, however, the stabilizingagent may be added to the oil in predetermined amounts lust sufficientto eflect the desired degree of improvement in stability.

In testing and demonstrating the improved stability of the new oilcompositions provided by the invention, use may be made of severalstandard testing procedures. A convenient test of stability ingeneral isthe so-called sludge accumulation test, designated as ASTM D670-42T,Method A. Bearing-corrosion tendencies may be determined by the Lausonengine test, and loadcarrying and general lubrication qualities may bedetermined by the Falex and static coeiiicient of friction tests,respectively. These various tests are described more fully hereinafter.

The following examples will illustrate several ways in which theprinciple of the invention hasbeen applied, but are not to be construedas limiting the same. All proportions are specified as parts by weight.

nxmmr Preparation of amine salts of bor'o-diol complexes The complex oi.boric acid and ethylene glycol was prepared by heating a mixture of 248.parts (4 mols) of ethylene glycol and 123.6 parts (2 mols) of boric acidin a flask fitted with a mechanical stirrer, thermometer, and refluxwater as trap. The flask and contents were initially heated at atemperature of about 100 C. for 1 hour, after which time 100 parts oftoluene were added and the heating, was continued at reflux temperaturewhile collecting water in the trap. Approximately 114 parts of waterwere collected n this manner. When the temperature of the contents ofthe flask reached about 121 C., the water trap was disconnected and thetoluene was distilled off until the temperature reached about 200 C.Upon cooling and standing overnight, the boroethylene glycol complex wasobtained as a white powdery solid'having a melting point of about Amixture of 17.1 parts (0.1 mol+30% excess) of the boro-ethylene glycolcomplex so prepared and 24.1 parts (0.1 mol) of hexadecylamine wasplaced in a flask and heated at a temperature or about 150 C. for 20minutes. It was then allowed to cool to about 50 C., and approximately200 parts of benzene were added. The mixture was then heated at refluxtemperature for 1 hour, after which it was cooled and flltered to removea small quantity'of unreacted complex. The benzene was then distilledoff, and the product was dried in a vacuum oven. The hexadecylamine saltof the boro-ethylene glycol complex so obtained was a yellow waxy solidhaving a. melting point of about 60-69 C.

A number of amine salts of diflerent boro-diol 7 complexes were preparedby the procedure just co Triethalnolamine salt 01 bore-ethylene yco'Hexadecylamine salt of boromtechol.--

'5 described. The properties of these products are tabulated below:

oi sludge formation one sample was removed and the sludge contentdetermined in the usual man- TABLE I Solubility Product Appearance EtherHexane Benzene Alcohol gfi Yellow waxy solld.

Hexadecylamiue salt of bore-ethylene cygigfi l rylamine salt ofbore-ethylene Brown waxy solid Brown semi-liquid.

'Ian powder Brown viscous liquid Tan solid Triethanolamine salt ofboro-catechol... Hexadecylamine salt or barb-salicylic acid.

Trieitianolamine salt of bore-salicylic Hexadecylamine salt ofbore-propylene glycol.

Hexadecylamine salt of boro-trimethyl- Brown solid Brown waxy solid..-

Yellow waxy solid. one given Triethanolamine salt of boro-trimethyl-Brown semi-liquid.

ene glycol.

1 Solubility: l=lnsoluble; S=Soluble; S1. S.=Slightly Soluble; V.S.==Very Soluble; S. H.==Soluble Hot.

EXAMPLE II Sludge accumulation tests Compositions were preparedcomprising certain of the boro-diol complex amine salts set forth inExample I and a mineral oil base having the ner. The test was continuedwith samples being withdrawn and sludge determinations made at intervalsof time depending upon the apparent rate of sludge formation. When allfive samples had been used up in this manner, a curve was plotted of theamount of sludge formed versus following specifications: 30 time. Thetime required for formation of 0.1 Gravity 0 API 2&0 per cent by Weightof sludge was read from this viscosity F SUV 5 curve and taken as aconvenient value for comviscosity F" s v 5 parison purposes. The rate ofsludge formation Flash point a F 275 35 was determined from the slope ofthe curve. The Fire point, F 310 results of the tests carried out inthis manner are Neut. No 0.01 tabulated below:

TABLE II Stabilizing Agent Rate of gg f Sludge Forby Identity g; Qtlfmt1n'%/Day Sludge, Days None (Base oil alone) 0.0 0.010 10Triethanolamine salt of bow-ethylene glycol. 03 0.008 34 Hexadecylaminesalt of boro-catechol 0. 3 0. 0035 34 Triethanolamine saltofboro-catechol o.3 0.0015 60 (est.) 'Iriethanolamine salt ofboro-trimethylene glycol 0.3 0.0035 38 Triethanolamiae salt ofboro-trunethylene yc 0.001 0.0095 12 'Iriethanolamine salt ofborosalicyiic acid." 0. 0. 001 43 Triethanolamine salt of borosalicylicacid." 0.001 0.010 14 Triethanolamine salt of boro-propylene glycol 030.003 38 1 Composition was prepared by dissolving the given amount ofstabilizing agent in the base 0 Each of the compositions was prepared byadding 0.3 per cent by weight of the amine salt to the base oil, afterwhich the mixture was warmed and stirred to promote solution. Thecomposition was then filtered to remove any of the amine salt which hadnot dissolved in the oil. Each of the compositions so prepared was thensubjected to the sludge accumulation test, ASTM D670-42T, Method A, asdescribed in ASTM Standards on Petroleum Products and Lubricants,December 1946, modified as follows: Instead of subjecting three samplesto the test and determining the amount of sludge formed at the end ofthe three given periods of time, five samples of each composition testedwere placed in the apparatus. After starting the test, the samples wereexamined from time to time and at the first evidence EXAMPLE III Lausonengine tests Compositions comprising three of the amine salts set forthin Example I and a mineral lubrieating oil were prepared as described inExample II. The base oil employed was a highly parafllnic lubricatingbase having the following specifications:

These compositions were tested for bearing-corrosion tendencies in thecrankcase of a standard 7 single-cylinder Lauson engine equipped with acopper-lead bearing and operated under the fol- -lowing conditions (L-4prototype procedure):

Water-jacket temperature, F 2l0- '-2 Oil temperature, F 280:2 Load, H. P1 Oil charge, ml 183 Air/fuel ratio 14.5:1.- -0.2 Speed, R. P. M 1820110After 4 hours of operation and at the end of each alternate 8-hourperiod thereafter, 23 ml. of fresh oil were added to the crankcase. Atthe end of the first 8-hour running period and. after each accumulative8-hour period thereafter, 10 ml. of the oil were withdrawn from thecrankcase, the crankcase volumewas corrected to 160 ml. and 23 ml. offresh oil were added. The copper-lead bearing was examined after each8-hour period, and at the end of 40 hours was weighed to determine theloss of weight. The piston was also examined at the end of 40 hours forevidence of varnish formation and was compared with a set of preparedstandards and given an arbitrary varnish rating value ranging from 10(no varnish formed) to (very heavy varnish formation). The results ofthese tests are tabulated below:

Load-carrying and lubrication tests In order to determine theload-carrying and lubrication qualities of the new compositions providedby the invention, a number of the compositions were subjected tosuitable tests. Loadcarrying properties were tested by the standardFalex seizure test employing steel V-blocks and steel pins. After a3-minute break-in period at 300 1bs. jaw load, followed by a 1-minuteperiod at 500 lbs. load, the load was increased in increments of 250lbs. with one minute running time until failure occurred. The load atfailure is a measure of the load-carrying properties of the compositionunder test. A measure of the lubrication properties of the newcompositions was obtained by a determination of the static coefilcientof friction at room temperature on a modifled Herschel-type machineemploying steel balls on a steel .race. The results of these tests aretabulated beW TABLE IV Stabilizing Agent Falex Static P t 05d at good.of er can a ure, riction Identity by Wt lbs None (Base Oil alone) 1, 0000. 29 Triethanolamine salt of borocatechol 0. 2 1, 500 0. 22Hexadecylamine salt of boroethylene glycol 0. l 1, 000 Hexadecylaminesalt of borotrimethylene glycol 0. 2 1, 250 0. Tricthanolamine salt ofborotrimethylene glycol 0. 2 1. 250 Hexadecylamine salt ofbore-salicylic acid 0. 2 1, 000 0. 21 Hexadecylamine salt ofboropropylene glycol 0. 2 1, 250

While the preceding examples illustrate the preparation and propertiesof compositions consisting only of a hydrocarbon oil base and aboro-diol complex amine salt stabilizing agent, it is to be understoodthat the compositions provided by the invention may contain otheradditive agents, e. g., pour point depressants, antifoam agents,viscosity index improvers, detergents, extreme pressure agents, etc.They may also contain corrosion inhibitors of the type which iseffective against corrosion in the presence of water or water vapor.Similarly, the base oil employed may be derived from various types ofstocks, e. g., parafl'lnic, naphthenic, or asphaltic stocks, or blendsthereof, as well as from synthetic hydrocarbon oils, and may be ofvarious degrees of refinement. They may vary widely in physicalcharacteristics depending upon the use to which theyare to be put.

Other modes of applying the principle of my invention may be employedinstead of those explained, change being made as regards the methods oringredients employed, provided the products defined by the followingclaims be obtained.

I claim:

1. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an amine salt of an acid compound of boricacid and a member selected from the group consisting of glycols andpolyhydroxy benzenes.

2. A composition of matter consisting essentially of a major proportionof a. hydrocarbon oil and a minor proportion of an amine salt of an acidcompound of boric acid and a member selected from the group consistingof glycols and polyhydroxy benzenes, said amine salt being present in anamount ranging from about 0.001 per cent by weight to the limit of itssolubility in said oil.

3. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an amine salt of an acid compound of boricacid and a glycol.

4. A composition of matter in accordance with claim 3 in which saidglycol is ethylene glycol.

5. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an amine salt of an acid compound of boricacid and a polyhydroxy benzene.-

6. A composition of matter in accordance with claim 5 in which saidpolyhydroxy benzene ls catechol.

7. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an aliphatic amine salt of an acid compoundof boric acid and a member selected from the group consisting of glycolsand polyhydroxy benzenes.

8.v A composition of matter consisting of essentially of a majorproportion of a hydrocarbon oil and between about 0.001 and about 0.5per cent by weight of the composition of an alkylolamine salt of an acidcompound of boric acid and a member selected from the group consistingof glycols and polyhydroxy benzenes.

9. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an aliphatic amine salt of an acid compoundof boric acid and a glycol.

10. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent byweight of the composition of an aliphatic amine salt of an acid compoundof boric acid and a dihydroxy benzene.

11. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about' '0.5 per cent byweight of the composition of the hexadecylamine salt of an acid compoundof boric acid and ethylene glycol. I

12. A composition of matter consisting essentially of a major proportionof a hydrocarbon oil and between about 0.001 and about 0.5 per cent 10by weight of the composition of the triethanolamine salt of an acidcompound of boric acid and catechol.

CHARLES E. TRAUTMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED'STATES PATENT

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A MAJOR PROPORTIONOF A HYDROCARBON OIL AND BETWEEN ABOUT 0.001 AND ABOUT 0.5 PER CENT BYWEIGHT OF THE COMPOSITION OF AN AMINE SALT BER SELECTED FROM THE GROUPCONSISTING OF GLYCOLS AND POLYHYDROXY BENZENES.